Communication entity and a method for transmitting a video data stream

ABSTRACT

A communication entity for transmitting a video data stream at a target transmission bit rate and corresponding method are provided. The communication entity comprises: a first scheduling instance configured to determine a preliminary transmission bit rate for forwarding the video data stream towards the user equipment; and a second scheduling instance configured to determine the target transmission bit rate based on the preliminary transmission bit rate and a set of video bit rates, the set of video bit rates comprising a first video bit rate associated with a first video quality and a second video bit rate associated with a second video quality, the first video bit rate being smaller than the second video bit rate, wherein the second scheduling instance is configured to select the preliminary transmission bit rate as the target transmission bit rate if the preliminary transmission bit rate does not exceed the first video bit rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/IB2019/000430, filed on Apr. 12, 2019, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present disclosure relate to the field of wirelesscommunication. More specifically, embodiments of the present disclosurerelate to a communication entity and a corresponding method fortransmitting a video data stream towards a user equipment over acommunication network.

BACKGROUND

In a typical HTTP Adaptive Streaming (HAS) system, a video file isencoded at different bitrates called representations (i.e. qualities),where each representation is split into segments of similar durations.All segments are stored into a web server and streamed to a client oneby one at the quality selected by the client via subsequent HTTPrequests. The HAS system does not include specifications on how thebitrate adaptation (quality selection) should be performed, but ratherdelegates to the client the task of applying its own adaptationstrategy.

However, all HAS clients are greedy in the sense that they are designedto get the highest possible Quality of Experience (QoE), i.e., theclients seek to download segments in the highest supported quality undergiven network conditions.

In the context of mobile networks, where video streaming services areaffected by mobility and cell-load variation, the HAS clientscontinually adapt the streaming quality to cope with throughputvariability. Since they operate greedily, adaptive video clients may onone hand overload cellular network resources, degrading the QoE of othernetwork users, and on the other hand they may suffer persistent bitrateoscillations. The root cause of the problem is that each HAS clientreacts myopically to variations in throughput generated by the presenceof other clients who compete for the same wireless resources.

Thus, the presence of adaptive video streams requires careful resourcemanagement in order to take into account such factors and avoid thedrawbacks of instability due to unnecessary switching of video bitrateand unfair resource allocation of HAS traffic against other traffictypes.

In general, existing approaches to the above identified problems can becast into one of three kinds: First, the streaming bitrate of HASclients can be limited to a fixed rate by network operators, which iscalled “static rate throttling”. This forces HAS clients to choose amedium quality in most services, in exchange for some benefits, such aszero rating contracts where the streaming traffic is not added to themonthly data cap of the user. The problem of static rate throttling isthat it does not adapt to network load: at low load users do not gethigh quality and therefore capacity is wasted, while at high load, thereis no mechanism to gradually control the HAS traffic.

Secondly, cross-layer allocation schemes profit from application-layerinformation of streaming, such as the play-back buffer occupancy. Theinformation is signaled to the base station scheduler in order to adjustits scheduling results. However, cross-layer signaling has to be adoptedby the operators of over-the-top (OTT) services and, so far, allattempts to standardize such signaling interfaces and protocols havefailed. Even with such standards in place, the conflicting technicalobjectives between OTTs and operators make their adoption unlikely. TheOTTs aim to maximize QoE for given networks limits while operators aimto maximize network efficiency for a given QoE limit. The OTTs havelittle or no interest in providing transparency to the lower protocollayers where the schedulers operate.

The third approach relates to “network-assisted bitrate adaptation”:Instead of obtaining application-layer information with cross-layersignaling directly, an alternative approach is to estimate keyapplication parameters at the network side (e.g., at a gateway, routeror base station). This estimation has accuracy errors and usually relieson Deep Packet Inspection (DPI) techniques. The DPI is computationalexpensive, technically difficult or impossible to implement withend-to-end encryption/privacy standards and may be restricted by legalconstraints, since it enables access to sensitive information that mayrepresent a breach of privacy.

A number of state-of-the-art studies on network optimization for mobilevideo streaming is discussed in detail in the following:

T-Mobile US, as part of the Binge On program launched in November 2015,uses a static limit of 1.5 Mbit/s for video streaming averaged over oneminute of video. This solution provides in most cases a medium qualityof 480p and does not provide a way to control quality oscillations,which is not efficient as it cannot adapt to the network load.

In the work “A cross-layer bandwidth allocation scheme for HTTP-basedvideo streaming in LTE cellular networks” by S. Colonnese et. al., IEEECommun. Lett., 2017, the authors proposed a cross-layer bandwidthallocation scheme that takes into account the channel quality as well asthe video quality requirements and encoding rate fluctuations of the HASvideo stream and minimizes the transmission delays experienced by users.However, this work relies on coordination between OTTs and operators.

In the work “SAP: Stall-aware pacing for improved dash video experiencein cellular networks” by A. H. Zahran et. al. in Proc. 8th ACM onMultimedia Systems Conference, New York, 2017, the authors leveragedboth network and client state information to optimize the pacing ofindividual video flows in order to reduce video stalls. However, thiswork assumes that the current video buffer level at the client is knownat the scheduler and does not take into account quality oscillations.

In the work “Improving QoE and fairness in HTTP adaptive streaming overLTE network” by S. Cical et. al., IEEE Trans. Circuits Syst. VideoTechnol., 2016, the share of radio resources is optimized according tovideo content characteristics, playout buffer levels and channelconditions. This work requires Channel State Information (CSI) updatesto set up Guaranteed Bit Rates (GBRs). Moreover, it ignores qualitychanges and requires close coordination between a HAS server, clientsand a base station.

In the work “A scheduling framework for adaptive video delivery overcellular networks” by J. Chen et. al. in Proc. 19th Annu. Int. Conf.Mobile Computing and Networking, ser. MobiCom '13. New York, 2013, theauthors optimally computed the bitrate allocation for each user andincludes a scheduler and per-flow shapers to enforce bitrate stabilityfor each flow. This work provides a gateway-level solution and performsnetwork side bitrate adaptation. However, it is not efficient fordynamic scenarios where it will generate quality switches due to userarrival/departure and mobility.

U.S. Ser. No. 13/789,462 provides an estimation of video bufferoccupancy and video stream characteristics (bitrate, buffer delay). Thisinformation is then used by the base station scheduler to adjust itsscheduling results. However, it relies on access to packet content andmetadata information to get the buffer occupancy estimation.

EP2016/082709 proposes a scheduler that assigns resources based on thetype of video frames (I, P, B). However, it requires a proxy server toclassify each data packet to the video frame type, which is not an easytask with data encryption.

US2014/018657 is based on identifying the bit rate that can maintain aparticular video quality of a Dynamic Adaptive Streaming over HTTP(DASH) client. It uses a virtual player to lock the bit rate for aparticular time interval; however, it does not take into considerationquality oscillations and it does not provide a way to have efficient andfair utilization of resources among different types of traffic.

In light of the above, there is still a need for an improvedcommunication entity and a corresponding method, allowing fortransmitting a video data stream to a user equipment more efficiently.

SUMMARY

It is an object of the disclosure to provide an improved communicationentity and a corresponding method for transmitting a video data streamtowards a user equipment over a communication network more efficiently.

The foregoing and other objects are achieved by the subject matter ofthe independent claims. Further implementation forms are apparent fromthe dependent claims, the description and the figures.

Generally, the present disclosure relates to scheduling of radioresources in mobile networks in the presence of adaptive streamingusers. This scheduling is performed in real time by a new instance thatcooperates with existing schedulers at a base station. This newmechanism ensures video quality stability for adaptive streaming users,as well as efficient and fair utilization of network resources among allusers. The disclosure focuses on the specific traffic type of HTTPAdaptive Streaming (HAS), which is a class of application protocols forthe delivery of multimedia data (i.e., video and audio) based on theHypertext Transfer Protocol (HTTP). Common specifications are DynamicAdaptive Streaming over HTTP (DASH) and HTTP Live Streaming (HLS).

More specifically, embodiments of the disclosure provide a newscheduling instance (also referred to as “second scheduling instance”hereafter) which is located at the base station and in closecollaboration with the existing scheduler of the base station (alsoreferred to as “first scheduling instance” hereafter). The functionalityof the second scheduling instance can be summarized as follows:

First, the second scheduling instance receives the instantaneous rateand the average rate of HAS users from the main scheduler, i.e. thefirst scheduling instance. Secondly, the second scheduling instanceretrieves the set of video bitrates for each HAS user, for example byaccessing a bitrate database or by querying the set directly from theservice provider. It adjusts the output of the first schedulinginstance, i.e. the average rate of HAS users, by taking into account theset of available video bitrates. This is achieved by adjusting the ratein order to be equal to the highest video bitrate that is lower than therate.

Furthermore, the second scheduling instance schedules the HAS users pertime slot in order to achieve the target rate by utilizing a fairscheduling policy. The results are sent to the main scheduler (i.e. thefirst scheduling instance), so that the main scheduler can forward allscheduling results for HAS and non-HAS users to the transmitter of thebase station. Also, the second scheduling instance informs the mainscheduler about the non-allocated resources, so that they can be usedfor non-HAS users and thus capacity is not wasted.

Thus, according to a first aspect the disclosure relates to acommunication entity for transmitting a video data stream towards a userequipment over a communication network at a target transmission bitrate, wherein the communication entity comprises: a first schedulinginstance configured to determine a preliminary transmission bit rate forforwarding the video data stream towards the user equipment; and asecond scheduling instance configured to determine the targettransmission bit rate upon the basis of the preliminary transmission bitrate and a set of video bit rates, the set of video bit rates comprisinga first video bit rate and a second video bit rate, the first video bitrate being associated with a first video quality, the second video bitrate being associated with a second video quality, the first video bitrate being smaller than the second video bit rate, wherein the secondscheduling instance is configured to select the preliminary transmissionbit rate as the target transmission bit rate if the preliminarytransmission bit rate does not exceed the first video bit rate.

Thus, an improved communication entity is provided, allowing fortransmitting a video data stream towards a user equipment over acellular communication network in an efficient manner.

In a further possible implementation form of the first aspect, thesecond scheduling instance is configured to compare the preliminarytransmission bit rate to the second video bit rate if the preliminarytransmission bit rate exceeds the first video bit rate, and to selectthe second video bit rate as the target transmission bit rate if thesecond video bit rate does not exceed the preliminary transmission bitrate or to select the first video bit rate as the target transmissionbit rate if the second video bit rate exceeds the preliminarytransmission bit rate.

In a further possible implementation form of the first aspect, the setof video bit rates comprises a plurality of video bit rates beingassociated with a plurality of video qualities, and wherein the secondscheduling instance is configured to determine a maximum video bit rateamong those video bit rates from the plurality of video bit rates thatare smaller than the preliminary transmission bit rate, or to determinea lowest video bit rate from the plurality of video bit rates that issmaller than the preliminary transmission bit rate, wherein thecommunication entity is configured to select the respectively determinedvideo bit rate as the target transmission bit rate.

In a further possible implementation form of the first aspect, thecommunication entity is configured to transmit a further video datastream towards a further user equipment at a further target transmissionbit rate, wherein the first scheduling instance is configured todetermine a further preliminary transmission bit rate for forwarding thefurther video data stream towards the further user equipment; andwherein the second scheduling instance is configured to determine thefurther target transmission bit rate upon the basis of the furtherpreliminary transmission bit rate and the set of video bit rates,wherein the second scheduling instance is configured to select thefurther preliminary transmission bit rate as the further targettransmission bit rate if the further preliminary transmission bit ratedoes not exceed the first video bit rate. Alternatively, the secondscheduling instance is configured to determine the further targettransmission bit rate upon the basis of the further preliminarytransmission bit rate and a further set of video bit rates, the furtherset of video bit rates comprising a third video bit rate and a fourthvideo bit rate, the third video bit rate being associated with a thirdvideo quality, the fourth video bit rate being associated with a fourthvideo quality, the third video bit rate being smaller than the fourthvideo bit rate, wherein the second scheduling instance is configured toselect the further preliminary transmission bit rate as the furthertarget transmission bit rate if the further preliminary transmission bitrate does not exceed the third video bit rate.

In a further possible implementation form of the first aspect, the firstscheduling instance is configured to schedule first radio resources ofthe communications entity for transmission of the video data streamtowards the user equipment, and to schedule second radio resources ofthe communications entity for other data communications.

The other data communications comprise, for instance, communications tonon-HAS user equipments and second radio resources are free radioresources which are not allocated for transmission of the video datastream yet.

In a further possible implementation form of the first aspect, thesecond scheduling instance is configured to receive the preliminarytransmission bit rate from the first scheduling instance and to providethe target transmission rate to the first scheduling instance, andwherein the first scheduling instance is configured to schedule radioresources of the communication entity for communication of the videodata stream towards the user equipment at the target transmission bitrate, or wherein the second scheduling instance is further configured toschedule radio resources of the communication entity for communicationof the video data stream towards the user equipment at the targettransmission bit rate and to provide information indicating thescheduled radio resources to the first scheduling instance forcommunication of the video data stream towards the user equipment at thetarget transmission bit rate.

In a further possible implementation form of the first aspect, thecommunication entity comprises a reception interface for receiving, inparticular over Internet, the video data stream according to the HTTPadaptive streaming technology.

In a further possible implementation form of the first aspect, the firstscheduling instance and the second scheduling instance form a compositescheduler of the communication entity, or wherein the first schedulinginstance and the second scheduling instance are separate schedulersimplemented in the communication entity.

In a further possible implementation form of the first aspect, thecommunication entity comprises a data base configured to store the setof video bit rates, or wherein the second scheduling instance isconfigured to retrieve the set of video data rates from a remote database over the communication network or over another communication link.

In a further possible implementation form of the first aspect, the firstscheduling instance is configured to determine an average transmissionbit rate averaging a plurality of transmission bit rates for differentvideo data streams within a time slot, and to determine the preliminarytransmission bit rate as the average transmission bit rate.

In a further possible implementation form of the first aspect, thecommunication entity comprises a transmission interface configured totransmit the video data stream towards the user equipment at the targettransmission bit rate.

In a further possible implementation form of the first aspect, thetransmission interface is configured to transmit the video data streamtowards the user equipment over a radio communication network.

In a further possible implementation form of the first aspect, thecommunication entity is a base station or an eNodeB.

In a further possible implementation form of the first aspect, thesecond scheduling instance is configured to determine a best userequipment i_(c)*(t) from a plurality of user equipments for allocationof radio resource c of the communication entity at a time slot t by thefollowing equation:

${{{for}c} \in K}{{i_{c}^{*}(t)} = \left\{ \begin{matrix}{{{{\arg\max}_{i}\left( {{{\overset{\_}{r}}_{i}(t)} - {\gamma_{i}(t)}} \right)}{\Gamma_{i}^{c}(t)}}\ ,} & {{{if}{\max_{i}\left( {{{\overset{\_}{r}}_{i}(t)} - {\gamma_{i}(t)}} \right)}} \geq 0} \\{{i_{v}\ ,}\ } & {otherwise}\end{matrix} \right.}$where K indicates available radio resources, r _(i)(t) indicates atarget transmission bit rate for transmission of a video data streamfrom the communication entity to one of the plurality of user equipmentsi, γ_(i)(t) indicates a real transmission bit rate for transmission of avideo data stream from the communication entity to the respective userequipment i, Γ_(i) ^(c)(t) indicates an instantaneous bit rate for therespective user equipment i at the time slot t for the radio resource cand i_(v) indicates a user equipment for other data communications withthe communication entity, wherein the first scheduling instance isconfigured to provide the instantaneous bit rate Γ_(i) ^(c)(t) for therespective user equipment i to the second scheduling instance.

According to a second aspect the disclosure relates to a method fortransmitting a video data stream towards a user equipment over acommunication network at a target transmission bit rate by acommunication entity. The method comprises the following steps:determining a preliminary transmission bit rate for forwarding the videodata stream towards the user equipment by a first scheduling instance ofthe communication entity; and determining the target transmission bitrate upon the basis of the preliminary transmission bit rate and a setof video bit rates at a second scheduling instance, wherein the set ofvideo bit rates comprises a first video bit rate and a second video bitrate, the first video bit rate being associated with a first videoquality, the second video bit rate being associated with a second videoquality, the first video bit rate being smaller than the second videobit rate, wherein the second scheduling instance selects the preliminarytransmission bit rate as the target transmission bit rate if thepreliminary transmission bit rate does not exceed the first video bitrate.

Thus, an improved method is provided, allowing for transmitting a videodata stream from a communication entity towards a user equipment over acommunication network in an efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the disclosure will be described with respect tothe following figures, wherein:

FIG. 1 shows a schematic diagram illustrating a communication systemcomprising a communication entity according to an embodiment and a userequipment according to an embodiment;

FIG. 2 shows a schematic diagram illustrating a communication systemcomprising a communication entity according to an embodiment and aplurality of user equipments according to an embodiment;

FIG. 3 shows a schematic diagram illustrating an algorithm for radioresource allocation used by a scheduling instance according to anembodiment;

FIG. 4 shows a schematic diagram illustrating video quality dynamics ofa typical user over time according to a proportional fair scheduler;

FIG. 5 shows a schematic diagram illustrating video quality dynamics ofa typical user over time according to an embodiment;

FIG. 6 shows a performance comparison between a scheduling instanceaccording to an embodiment and a proportional fair scheduler for RANslicing;

FIG. 7 shows a performance comparison between a scheduling instanceaccording to an embodiment and a proportional fair scheduler for RANsharing; and

FIG. 8 shows a schematic diagram illustrating a method of transmitting avideo data stream towards a user equipment by a communication entityaccording to an embodiment.

In the various figures, identical reference signs will be used foridentical or at least functionally equivalent features.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, reference is made to the accompanyingdrawings, which form part of the disclosure, and in which are shown, byway of examples, specific aspects in which the present disclosure may beplaced. It is understood that other aspects may be utilized andstructural or logical changes may be made without departing from thescope of the present disclosure. The following detailed description,therefore, is not to be taken in a limiting sense, as the scope of thepresent disclosure is defined be the appended claims.

For instance, it is understood that a disclosure in connection with adescribed method may also hold true for a corresponding device or systemconfigured to perform the method and vice versa. For example, if aspecific method step is described, a corresponding device may include aunit to perform the described method step, even if such unit is notexplicitly described or illustrated in the figures. Further, it isunderstood that the features of the various exemplary aspects describedherein may be combined with each other, unless specifically notedotherwise.

Generally, the present disclosure relates to a communication entity thatworks well under dynamic scenarios due to channel and load variation fortransmitting a video data stream towards a user equipment over acommunication network. The present disclosure focuses on the specifictraffic type of HTTP Adaptive Streaming (HAS), which is a class ofapplication protocols for the delivery of multimedia data (i.e., videoand audio) based on the Hypertext Transfer Protocol (HTTP). Commonspecifications are Dynamic Adaptive Streaming over HTTP (DASH) and HTTPLive Streaming (HLS).

Since the majority of multimedia traffic is generated by HAS protocols(see Sandvine, “Global Internet Phenomena: Latin America & NorthAmerica”, White Paper, 2016), the large portion of multimedia traffic inthe Internet (see Cisco, “Cisco Visual Networking Index: Forecast andTrends, 2017-2022”, White Paper, 2019) as well as its specific servicerequirements make it highly desirable to optimize network resourcemanagement in the presence of HAS users.

Embodiments of the disclosure provide a fair scheduling instance that isable to arbitrate multiple traffic flows, where HAS flows are controlledin a stable manner. Besides, embodiments of the present disclosure canbe combined with any existing scheduling policy implemented at a basestation, as well as with any HAS client adaptation policy, facilitatingquick and convenient deployments.

As will be described in more detail in the following under reference toFIGS. 1 and 2 , embodiments of the disclosure enable a new schedulinginstance (also referred to as “second scheduling instance” hereafter andas “ADVISER” in figures) which ensures bitrate stability for the HASusers (also referred to as user equipments hereafter). This schedulinginstance is located at the base station and is in close collaborationwith the existing scheduler of the base station (also referred to as“first scheduling instance” hereafter).

The second scheduling instance is configured to calculate the schedulingresults for HAS user equipments and to communicate them to the firstscheduling instance. In order to do this calculation, the secondscheduling instance receives information from the first schedulinginstance about the transmission bit rates of HAS user equipments (i.e.average and instantaneous transmission bit rates of user equipments),which is information that already exists at the first schedulinginstance.

The second scheduling instance is also configured to receive as input aset of video bit rates for each HAS user. This set of video bit ratescan be acquired by other methods, for example, by retrieving from abitrate database that contains a lookup table mapping source InternetProtocol (IP) addresses or Domain Name Servers (DNS) to a given serviceprovider and thus to the known bitrates of this provider, or by queryingdirectly from service providers, assuming that this coordination betweenthe operators and the over-the-top (OTT) service providers is feasible.

The set of video bitrates is used to find a target transmission bit ratefor each HAS user equipment. More precisely, this target transmissionbit rate is one of the values of the bitrate list, as this ensuresbitrate stability. Then, the second scheduling instance calculates thescheduling results of HAS users in order to achieve these targettransmission bit rates in a fair way.

More specifically, FIG. 1 shows a schematic diagram illustrating acommunication network 100 comprising a communication entity 101according to an embodiment and a user equipment 107 according to anembodiment. In an embodiment, the communication entity 101 is a basestation or an eNodeB and the communication entity 101 is configured totransmit a video data stream towards the user equipment 107 over thecommunication network 100.

According to an embodiment, the communication entity 101 comprises areception interface for receiving, in particular over Internet, thevideo data stream according to the HTTP adaptive streaming technology aswell as a transmission interface configured to transmit the video datastream towards the user equipment 107. In particular, the transmissioninterface of the communication entity 101 is configured to transmit thevideo data stream towards the user equipment 107 over a radiocommunication network.

Similarly, FIG. 2 shows a schematic diagram illustrating a communicationnetwork comprising the communication entity 101 according to anembodiment and a plurality of user equipments 107 a-c according to anembodiment, wherein the communication entity 101 is configured totransmit a plurality of video data streams towards the plurality of userequipments 107 a-c over the communication network.

As can be taken from the detailed view shown in FIGS. 1 and 2 , thecommunication entity 101 comprises a first scheduling instance 103 and asecond scheduling instance 105. As shown in the embodiment of FIG. 2 ,the communication entity 101 further comprises a base stationtransmitter 205 for data transmission.

In an embodiment, the first scheduling instance 103 and the secondscheduling instance 105 form a composite scheduler of the communicationentity 101, or the first scheduling instance 103 and the secondscheduling instance 105 are separate schedulers implemented in thecommunication entity 101.

According to an embodiment, the first scheduling instance 103 isconfigured to determine a preliminary transmission bit rate forforwarding the video data stream towards the user equipment 107, whereinthe first scheduling instance 103 is configured to determine thepreliminary transmission bit rate as an average transmission bit rateaveraging a plurality of transmission bit rates for different video datastreams within a time slot.

According to an embodiment, the second scheduling instance 105 isconfigured to determine the target transmission bit rate upon the basisof the preliminary transmission bit rate and a set of video bit rates,wherein the set of video bit rates comprises a first video bit rateassociated with a first video quality and a second video bit rateassociated with a second video quality and wherein the first video bitrate being smaller than the second video bit rate.

In an embodiment, the communication entity 101 comprises a data basewhich is configured to store the set of video bit rates, or the secondscheduling instance 105 is configured to retrieve the set of video datarates from a remote data base 203 over the communication network 100 orover another communication link.

To determine the target transmission bit rate, the second schedulinginstance 105 is configured to select the preliminary transmission bitrate as the target transmission bit rate if the preliminary transmissionbit rate does not exceed the first video bit rate. Further, the secondscheduling instance 105 is configured to compare the preliminarytransmission bit rate to the second video bit rate if the preliminarytransmission bit rate exceeds the first video bit rate, and to selectthe second video bit rate as the target transmission bit rate if thesecond video bit rate does not exceed the preliminary transmission bitrate or to select the first video bit rate as the target transmissionbit rate if the second video bit rate exceeds the preliminarytransmission bit rate.

According to a further embodiment, the set of video bit rates cancomprise a plurality of video bit rates being associated with aplurality of video qualities, and the second scheduling instance 105 isconfigured to determine a maximum video bit rate among those video bitrates from the plurality of video bit rates that are smaller than thepreliminary transmission bit rate, or to determine a lowest video bitrate from the plurality of video bit rates that is smaller than thepreliminary transmission bit rate. Then, the communication entity 101 isconfigured to select the respectively determined video bit rate as thetarget transmission bit rate.

According to a further embodiment, the communication entity 101 cantransmit a further video data stream towards a further user equipment107 b at a further target transmission bit rate. The first schedulinginstance 103 is configured to determine a further preliminarytransmission bit rate for forwarding the further video data streamtowards the further user equipment 107 b.

Also, the second scheduling instance 105 is configured to determine thefurther target transmission bit rate upon the basis of the furtherpreliminary transmission bit rate and the set of video bit rates,wherein the second scheduling instance 105 is configured to select thefurther preliminary transmission bit rate as the further targettransmission bit rate if the further preliminary transmission bit ratedoes not exceed the first video bit rate.

Alternatively, the second scheduling instance 105 is configured todetermine the further target transmission bit rate upon the basis of thefurther preliminary transmission bit rate and a further set of video bitrates, wherein the further set of video bit rates comprises a thirdvideo bit rate associated with a third video quality and a fourth videobit rate associated with a fourth video quality and wherein the thirdvideo bit rate being smaller than the fourth video bit rate. The secondscheduling instance 105 is configured to select the further preliminarytransmission bit rate as the further target transmission bit rate if thefurther preliminary transmission bit rate does not exceed the thirdvideo bit rate.

Furthermore, the second scheduling instance 105 is configured to receivethe preliminary transmission bit rate from the first scheduling instanceand to provide the target transmission rate to the first schedulinginstance.

In an embodiment, the first scheduling instance 103 is configured toschedule radio resources of the communication entity 101 forcommunication of the video data stream towards the user equipment 107 atthe target transmission bit rate, or the second scheduling instance 105is further configured to schedule radio resources of the communicationentity 101 for communication of the video data stream towards the userequipment 107 at the target transmission bit rate and to provideinformation indicating the scheduled radio resources to the firstscheduling instance 103 for communication of the video data streamtowards the user equipment 107 at the target transmission bit rate.

In a further embodiment, the first scheduling instance 103 is configuredto schedule first radio resources of the communications entity 101 fortransmission of the video data stream towards the user equipment 107,and to schedule second radio resources of the communications entity 101for other data communications. The other data communications comprise,for instance, communications to non-HAS user equipments and second radioresources are remaining radio resources which are not allocated yet.

Finally, in an embodiment the second scheduling instance 105 isconfigured to determine a best user equipment i_(c)*(t) from theplurality of user equipments 107 a-c for allocation of radio resource cof the communication entity 101 at a time slot t by the followingequation:

${{{for}c} \in K}{{i_{c}^{*}(t)} = \left\{ \begin{matrix}{{{{\arg\max}_{i}\left( {{{\overset{\_}{r}}_{i}(t)} - {\gamma_{i}(t)}} \right)}{\Gamma_{i}^{c}(t)}}\ ,} & {{{if}{\max_{i}\left( {{{\overset{\_}{r}}_{i}(t)} - {\gamma_{i}(t)}} \right)}} \geq 0} \\{{i_{v}\ ,}\ } & {otherwise}\end{matrix} \right.}$where K indicates available radio resources, r _(i)(t) indicates atarget transmission bit rate for transmission of a video data streamfrom the communication entity 101 to one of the plurality of userequipments 107 a-c, γ _(i)(t) indicates a real transmission bit rate fortransmission of a video data stream from the communication entity to therespective user equipment i, Γ_(i) ^(c)(t) indicates an instantaneousbit rate provided by the first scheduling instance 103 for therespective user equipment i at the time slot t for the radio resource c,and i_(v) indicates a user equipment for other data communications withthe communication entity 101.

In summary, the functionalities of the first scheduling instance 103 andthe second scheduling instance 105 are listed as follows:

According to an embodiment, the first scheduling instance 103 can be anexisting base station scheduler (e.g. proportional fair) configured to:compute the average transmission bit rate of each HAS user equipment andsend it together with his/her instantaneous transmission bit rate to thesecond scheduling instance 105, wherein the computation of the averagetransmission bit rate is a standard process of the first schedulinginstance 103 for all users and the instantaneous rates are already knownat the first scheduling instance 103; get the scheduling results of theHAS users from the second scheduling instance 105, including thescheduling results of the HAS users and the set of used (or equivalentlyunused) radio resources; schedule the non-HAS users by using the freeradio resources and forward the scheduling results for all users (HASand non-HAS) to the base station transmitter 205 for data transmission.

According to an embodiment, the second scheduling instance 105 isconfigured to: get the instantaneous transmission bit rate and theaverage transmission bit rate of HAS users sent from the firstscheduling instance 103; retrieve the set of video bitrates (e.g. fromthe bitrate database 203) for each HAS user; calculate the targettransmission bit rate for each HAS user based on his/her averagetransmission bit rate and the set of video bitrates; schedule the HASusers per time slot according to their instantaneous transmission bitrate and the calculated target transmission bit rate by utilizing a fairscheduling policy; send the scheduling results and the set of used radioresources to the first scheduling instance 103.

The proposed functionalities are applicable to all HAS protocols. As aconsequence, the embodiments of the disclosure can schedule HAS trafficfor: video on demand (VoD) streaming; live streaming; DASH or HLSspecification; TCP or QUIC/UDP; with or without Transport Layer Security(TLS) and Secure Sockets Layer (SSL) encryption.

The embodiments of the disclosure offer the following advantages: norequired standardization of cross-layer interfaces, which is ofuncertain outcome and adoption; no direct access to theapplication-layer, avoiding violating user privacy and/or legalboundaries; no modification of existing base station schedulers,facilitating quick deployments; significant reduction of the number ofvideo quality switches, which is an important factor to achieve highQuality of Experience (QoE) for HAS traffic; fair and efficientutilization of radio resources across all network users by controllingthe greedy behavior of HAS users; simple design with low computationalrequirements that can be used in real-time scheduling; no dependencieson specific client side adaptation or requirements for network side HASadaptation; applicable to both Radio Access Network (RAN) slicing andRAN sharing architectures, as long as the scheduling instances knowswhich packet flows belong to HAS users.

Furthermore, the embodiments of the disclosure can be readily applied tothe following applications: traffic-aware schedulers for networkoptimization; bandwidth throttling, load control, admission control fortraffic shaping.

According to an embodiment, the second scheduling instance 105 receivesthe values of the average transmission bit rates calculated by the firstscheduling instance 103, wherein the average transmission bit rate canbe, for instance, computed by existing schedulers for every user i atevery time slot t 1 as follows:r _(i)(t)=(1−β)r _(i)(t−1)+βΣ_(c∈K)Γ_(i) ^(c)(t)I _({l) _(c) ^((t)=i}),where β is the memory of the averaging filter, c is the index ofresource block from the set K of available resources, Γ_(i) ^(c) (t) isthe instantaneous rate of user i at time slot t at resource c, I_({.})is the indicator function that is equal to 1 if its argument is true andis equal to 0 otherwise, and l _(c)(t) denotes the user that isvirtually allocated resource c at time slot t. It is to be noted thatthe value of l _(c)(t) is the output of the scheduler's allocationalgorithm and that the term virtual is used here in the sense that thisallocation is the preliminary allocation for HAS users that can bemodified later by the second scheduling instance 105.

Then, the target transmission bit rate r _(i)(t) for each HAS user i atevery time slot t is given by:

${{\overset{\_}{r}}_{i}(t)} = \left\{ \begin{matrix}{{r_{i}(t)}\ ,} & {\ {{{if}{r_{i}(t)}} \leq l_{1}^{i}}} \\{{\max\left\{ {{l_{j}^{i}❘{l_{j}^{i} \leq {r_{i}(t)}}},{1 \leq j \leq m}} \right\}},} & {otherwise}\end{matrix} \right.$where l_(j) ^(i) is the bitrate of video quality with index j∈{1, 2, . .. , m} and l_(j+1) ^(i)>l_(j) ^(i). The above equation indicates thatthe target rate is chosen to be equal to the highest video bitrate thatis below the provided rate r_(i)(t) from the first scheduling instance103.

According to another embodiment, once the target rate for each HAS useris calculated, the second scheduling instance 105 is now able to performthe actual resource allocation that can achieve these rates by using thealgorithm 300 as shown in FIG. 3 .

This algorithm 300 finds the best user i_(c)*(t) to allocate resource cat time slot t. The part at line 2 checks if all HAS users have averagethroughput γ_(i)(t) greater than their target rate r _(i)(t). If this istrue, then the resource c is not allocated to a HAS user and thus, isavailable for non-HAS users, denoted here as a virtual user i_(v).Otherwise, the resource is allocated in a fair manner to the user withmaximum (r _(i)(t)−γ_(i)(t))Γ_(i) ^(c)(t), i.e. a term that takes intoaccount the instantaneous rate as well as the gap between the targetrate and the actual average throughput of the user.

Finally, it should be noted that γ_(i)(t) is calculated in a similar wayas the first scheduling instance calculates r_(i)(t), as shown below:γ_(i)(t)=(1−β)γ_(i)(t−1)+βΣ_(c∈K)Γ_(i) ^(c)(t)I _({i) _(c) _(*(t)=i}),where the difference from the equation for r_(i)(t) is that i_(c)*(t) isused instead of l _(c)(t) at the indicator function. This differenceleads to an average throughput γ_(i)(t) that is close to the averagerate r_(i)(t), but is modified in a way that its value stabilizes arounda video bitrate. In the case of RAN slicing, it is to be noted that onlya part of the total resources is available for the HAS users, and thusthe summation in the above equation should be performed only over thispart of resources.

FIGS. 4 to 7 assess the performance of the embodiments of the disclosurein comparison with that of a proportional fair (PF) scheduler. Theperformance of the embodiments of the disclosure is studied in a3GPP-compliant LTE system-level simulator. In order to have a baselinefor comparison purposes, the performance of a proportional fair (PF)scheduler is also studied. The key parameters of the simulation setupare listed below: cellular topology with multiple users; mixed trafficwith HAS and non-HAS users at the same time; a set of video bitratestaken from the bitrate values used in a popular platform for videosharing; heavy-tail distribution of the duration of a HAS session with amean of 240 seconds; random arrivals of users with users leaving thesystem upon completion of the session; buffer-based HAS adaptationpolicy.

FIG. 4 shows the video quality dynamics over time of a typical user whenthe proportional fair (PF) scheduler is used. The multiple available HASbitrate levels are shown as horizontal dotted lines. Moreover, userarrival and departures in the system are represented by the verticaldotted lines. This figure highlights the greedy policy of HAS clientswith frequent fluctuations 401 of the video bitrate. Indeed, since theavailable throughput 403 is almost always between two bitrates, a HASclient alternates between these two qualities and thus, tends to chooseoften a video bitrate that is not sustainable at the current throughput403 causing these oscillations 401.

On the other hand, FIG. 5 shows the video quality dynamics of a typicaluser according to the embodiments of the disclosure. As seen from FIG. 5, the achieved throughput γ_(i)(t) 501 is set equal to a video bitrate503, besides short periods of time where a transition happens due to auser arrival or departure. In this way, the buffer level is stabilizedand there is a large decrease of quality oscillations.

FIG. 6 shows a comparison between a scheduling instance (called ADVISER)according to an embodiment and a proportional fair (PF) scheduler interms of two Quality-of-Experience metrics (i.e. average video qualityand number of quality switches) for RAN slicing under an increasingarrival rate of users. Each user takes one of three values of channelrates {3, 6, 9} Mbps with equal probability. The normalized number ofswitches is measured as the ratio between the number of switchesoccurred and the total number of segments transmitted. It can beobserved that the switching rate is greatly reduced for the ADVISERcompared to that for a PF scheduler, i.e., by a percentage ranging from80.7% to 85.7% overall. The average video quality slightly decreases,but this decrease has a negligible impact on the Quality of Experience(QoE) of the HAS user.

FIG. 7 shows a comparison between a scheduling instance (called ADVISER)according to an embodiment and a proportional fair (PF) scheduler interms of two Quality-of-Experience metrics (i.e. average video qualityand number of quality switches) for a RAN sharing scenario where the HASand non-HAS users have the same pool of bandwidth resources. Here theflow size for non-HAS users is independent and exponentially distributedwith a mean of 124 seconds. It can be seen that the performance issimilar to the performance in the scenario with RAN slicing as shown inFIG. 6 , this time with a decrease in number of quality switches of upto 86.6%.

It is worth noting that, with the simulation setup used for the resultsshown in FIGS. 6 and 7 , there is no video stall occurred for any HASuser, because the average rate of the scheduler was higher than thelowest bitrate. Those scenarios where stalls are likely to happen arealso studied and it is verified that the embodiments of the presentdisclosure do not suffer from increased stalling events compared to a PFscheduler. Overall, the achieved quality of experience for HAS users ishigher with the embodiments of the present disclosure.

FIG. 8 shows a schematic diagram illustrating a method 800 oftransmitting a video data stream towards a user equipment 107 over acommunication network at a target transmission bit rate by acommunication entity 101.

The method 800 comprises a first step 801 of determining a preliminarytransmission bit rate for forwarding the video data stream towards theuser equipment 107 by a first scheduling instance 103 of thecommunication entity 101.

The method 800 comprises a further step 803 of determining the targettransmission bit rate upon the basis of the preliminary transmission bitrate and a set of video bit rates at a second scheduling instance 105,wherein the set of video bit rates comprises a first video bit rate anda second video bit rate, the first video bit rate being associated witha first video quality, the second video bit rate being associated with asecond video quality, the first video bit rate being smaller than thesecond video bit rate, wherein the second scheduling instance 105selects the preliminary transmission bit rate as the target transmissionbit rate if the preliminary transmission bit rate does not exceed thefirst video bit rate.

While a particular feature or aspect of the disclosure may have beendisclosed with respect to only one of several implementations orembodiments, such feature or aspect may be combined with one or moreother features or aspects of the other implementations or embodiments asmay be desired and advantageous for any given or particular application.Furthermore, to the extent that the terms “include”, “have”, “with”, orother variants thereof are used in either the detailed description orthe claims, such terms are intended to be inclusive in a manner similarto the term “comprise”. Also, the terms “exemplary”, “for example” and“e.g.” are merely meant as an example, rather than the best or optimal.The terms “coupled” and “connected”, along with derivatives may havebeen used. It should be understood that these terms may have been usedto indicate that two elements cooperate or interact with each otherregardless whether they are in direct physical or electrical contact, orthey are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, itwill be appreciated by those of ordinary skill in the art that a varietyof alternate and/or equivalent implementations may be substituted forthe specific aspects shown and described without departing from thescope of the present disclosure. This application is intended to coverany adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in aparticular sequence with corresponding labeling, unless the claimrecitations otherwise imply a particular sequence for implementing someor all of those elements, those elements are not necessarily intended tobe limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent tothose skilled in the art in light of the above teachings. Of course,those skilled in the art readily recognize that there are numerousapplications of the disclosure beyond those described herein. While thepresent disclosure has been described with reference to one or moreparticular embodiments, those skilled in the art recognize that manychanges may be made thereto without departing from the scope of thepresent disclosure. It is therefore to be understood that within thescope of the appended claims and their equivalents, the disclosure maybe practiced otherwise than as specifically described herein.

What is claimed is:
 1. A communication entity for transmitting a videodata stream towards a user equipment over a communication network at atarget transmission bit rate, the communication entity comprising: amemory storing instructions; and a processor coupled to the memory toexecute the instructions to: determine a preliminary transmission bitrate for forwarding the video data stream towards the user equipment;determine the target transmission bit rate based on the preliminarytransmission bit rate and a set of video bit rates, wherein the set ofvideo bit rates comprises a first video bit rate and a second video bitrate, the first video bit rate is associated with a first video quality,the second video bit rate is associated with a second video quality, thefirst video bit rate is smaller than the second video bit rate, andselect the preliminary transmission bit rate as the target transmissionbit rate in response to the preliminary transmission bit rate notexceeding the first video bit rate; determine a further preliminarytransmission bit rate for forwarding a further video data stream towardsa further user equipment; and determine a further target transmissionbit rate based on the further preliminary transmission bit rate and theset of video bit rates; select the further preliminary transmission bitrate as the further target transmission bit rate in response to thefurther preliminary transmission bit rate not exceeding the first videobit rate; or determine the further target transmission bit rate based onthe further preliminary transmission bit rate and a further set of videobit rates, wherein the further set of video bit rates comprises a thirdvideo bit rate and a fourth video bit rate, the third video bit rate isassociated with a third video quality, the fourth video bit rate isassociated with a fourth video quality, the third video bit rate issmaller than the fourth video bit rate; and select the furtherpreliminary transmission bit rate as the further target transmission bitrate in response to the further preliminary transmission bit rate notexceeding the third video bit rate.
 2. The communication entityaccording to claim 1, wherein the processor further executes theinstructions to: compare the preliminary transmission bit rate to thesecond video bit rate in response to the preliminary transmission bitrate exceeding the first video bit rate, and select the second video bitrate as the target transmission bit rate in response to the second videobit rate not exceed the preliminary transmission bit rate; or select thefirst video bit rate as the target transmission bit rate in response tothe second video bit rate exceeding the preliminary transmission bitrate.
 3. The communication entity according to claim 1, wherein the setof video bit rates comprises a plurality of video bit rates associatedwith a plurality of video qualities, and wherein the processor furtherexecutes the instructions to: determine a maximum video bit rate amongthose video bit rates from the plurality of video bit rates that aresmaller than the preliminary transmission bit rate, or determine alowest video bit rate from the plurality of video bit rates that issmaller than the preliminary transmission bit rate, and select therespectively determined video bit rate as the target transmission bitrate.
 4. The communication entity according to claim 1, wherein theprocessor further executes the instructions to: schedule first radioresources of the communication entity for transmission of the video datastream towards the user equipment, and schedule second radio resourcesof the communication entity for other data communications.
 5. Thecommunication entity according to claim 1, wherein the processor furtherexecutes the instructions to: receive the preliminary transmission bitrate from the first scheduling instance and schedule radio resources ofthe communication entity for communication of the video data streamtowards the user equipment at the target transmission bit rate; andprovide information indicating the scheduled radio resources forcommunication of the video data stream towards the user equipment at thetarget transmission bit rate.
 6. The communication entity according toclaim 1, further comprising: a reception interface configured tocooperate with the processor to receive, over Internet, the video datastream according to the HTTP adaptive streaming technology.
 7. Thecommunication entity according to claim 1, wherein the communicationentity comprises: a data base configured to store the set of video bitrates, or wherein the processor executes the instructions to: retrievethe set of video data rates from a remote data base over thecommunication network or over another communication link.
 8. Thecommunication entity according to claim 1, wherein the processorexecutes the instructions to: determine an average transmission bit rateaveraging a plurality of transmission bit rates for different video datastreams within a time slot, and determine the preliminary transmissionbit rate as the average transmission bit rate.
 9. The communicationentity according to claim 1, further comprising: a transmissioninterface configured to cooperate with the processor to transmit thevideo data stream towards the user equipment at the target transmissionbit rate.
 10. The communication entity according to claim 9, wherein thetransmission interface is configured to transmit the video data streamtowards the user equipment over a radio communication network.
 11. Thecommunication entity according to claim 1, wherein the communicationentity is a base station or an evolved Node B (eNodeB).
 12. Thecommunication entity according to claim 1, wherein the processorexecutes the instructions to: determine a best user equipment i_(c)*(t)from a plurality of user equipments for allocation of radio resource cof the communication entity at a time slot t by the following:${{{for}c} \in {K{i_{c}^{*}(t)}}} = \left\{ \begin{matrix}{{\arg{\max_{i}\left( {{\overset{¯}{r_{i}}(t)} - {\gamma_{i}(t)}} \right)}{\Gamma_{i}^{c}(t)}}\ ,\ {{{if}{}{\max_{i}\left( {{{\overset{¯}{r}}_{i}(t)} - {\gamma_{i}(t)}} \right)}} \geq 0}} \\{i_{v}\ {,\ {{othe}rwise}}}\end{matrix} \right.$ wherein K indicates available radio resources, r_(i)(t) indicates a target transmission bit rate for transmission of avideo data stream from the communication entity to one of the pluralityof user equipments i, γ_(i)(t) indicates a real transmission bit ratefor transmission of a video data stream from the communication entity tothe respective user equipment i, Γ_(i) ^(c)(t) indicates aninstantaneous bit rate for the respective user equipment i at the timeslot t for the radio resource c and i_(v) indicates a user equipment forother data communications with the communication entity.
 13. Atransmission method for transmitting a video data stream towards a userequipment over a communication network at a target transmission bit rateby a communication entity, the transmission method comprising:determining a preliminary transmission bit rate for forwarding the videodata stream towards the user equipment by a first scheduling instance ofthe communication entity; determining the target transmission bit ratebased on the preliminary transmission bit rate and a set of video bitrates at a second scheduling instance, wherein the set of video bitrates comprises a first video bit rate and a second video bit rate, thefirst video bit rate is associated with a first video quality, thesecond video bit rate is associated with a second video quality, thefirst video bit rate is smaller than the second video bit rate, whereinthe second scheduling instance selects the preliminary transmission bitrate as the target transmission bit rate in response to the preliminarytransmission bit rate not exceeding the first video bit rate;determining a further preliminary transmission bit rate for forwarding afurther video data stream towards a further user equipment; anddetermining a further target transmission bit rate based on the furtherpreliminary transmission bit rate and the set of video bit rates; selectthe further preliminary transmission bit rate as the further targettransmission bit rate in response to the further preliminarytransmission bit rate not exceeding the first video bit rate; ordetermining the further target transmission bit rate based on thefurther preliminary transmission bit rate and a further set of video bitrates, wherein the further set of video bit rates comprises a thirdvideo bit rate and a fourth video bit rate, the third video bit rate isassociated with a third video quality, the fourth video bit rate isassociated with a fourth video quality, the third video bit rate issmaller than the fourth video bit rate; and selecting the furtherpreliminary transmission bit rate as the further target transmission bitrate in response to the further preliminary transmission bit rate notexceeding the third video bit rate.
 14. The method according to claim13, further comprising: comparing, by the second scheduling instance,the preliminary transmission bit rate to the second video bit rate inresponse to the preliminary transmission bit rate exceeding the firstvideo bit rate, and selecting, by the second scheduling instance, thesecond video bit rate as the target transmission bit rate in response tothe second video bit rate not exceeding the preliminary transmission bitrate or to select the first video bit rate as the target transmissionbit rate in response to the second video bit rate exceeding thepreliminary transmission bit rate.
 15. The method according to claim 13,wherein the set of video bit rates comprises a plurality of video bitrates being associated with a plurality of video qualities, and themethod further comprises: determining, by the second schedulinginstance, a maximum video bit rate among those video bit rates from theplurality of video bit rates that are smaller than the preliminarytransmission bit rate, or determining, by the second schedulinginstance, a lowest video bit rate from the plurality of video bit ratesthat is smaller than the preliminary transmission bit rate; andselecting, by the communication entity, the respectively determinedvideo bit rate as the target transmission bit rate.
 16. The methodaccording to claim 13, further comprising: scheduling, by the firstscheduling instance, first radio resources of the communication entityfor transmission of the video data stream towards the user equipment,and scheduling, by the first scheduling instance, second radio resourcesof the communication entity for other data communications.
 17. Themethod according to claim 13, further comprising: receiving, by thesecond scheduling instance, the preliminary transmission bit rate fromthe first scheduling instance and providing, by the second schedulinginstance, the target transmission rate to the first scheduling instance,and scheduling, by the first scheduling instance, radio resources of thecommunication entity for communication of the video data stream towardsthe user equipment at the target transmission bit rate, or scheduling,by the second scheduling instance, radio resources of the communicationentity for communication of the video data stream towards the userequipment at the target transmission bit rate and to provide informationindicating the scheduled radio resources to the first schedulinginstance for communication of the video data stream towards the userequipment at the target transmission bit rate.
 18. The method accordingto claim 13, comprising: determining an average transmission bit rateaveraging a plurality of transmission bit rates for different video datastreams within a time slot, and determining the preliminary transmissionbit rate as the average transmission bit rate.
 19. A non-transitorycomputer-readable medium storing processor executable instructions forimplementing a transmission method for transmitting a video data streamtowards a user equipment over a communication network at a targettransmission bit rate, the instructions, when executed cause acommunication entity to: determine a preliminary transmission bit ratefor forwarding the video data stream towards the user equipment;determine the target transmission bit rate upon the basis of thepreliminary transmission bit rate and a set of video bit rates, whereinthe set of video bit rates comprises a first video bit rate and a secondvideo bit rate, the first video bit rate is associated with a firstvideo quality, the second video bit rate is associated with a secondvideo quality, the first video bit rate is smaller than the second videobit rate, and select the preliminary transmission bit rate as the targettransmission bit rate in response to the preliminary transmission bitrate not exceeding the first video bit rate; determine a furtherpreliminary transmission bit rate for forwarding a further video datastream towards a further user equipment; and determine a further targettransmission bit rate based on the further preliminary transmission bitrate and the set of video bit rates; select the further preliminarytransmission bit rate as the further target transmission bit rate inresponse to the further preliminary transmission bit rate not exceedingthe first video bit rate; or determine the further target transmissionbit rate based on the further preliminary transmission bit rate and afurther set of video bit rates, wherein the further set of video bitrates comprises a third video bit rate and a fourth video bit rate, thethird video bit rate is associated with a third video quality, thefourth video bit rate is associated with a fourth video quality, thethird video bit rate is smaller than the fourth video bit rate; andselect the further preliminary transmission bit rate as the furthertarget transmission bit rate in response to the further preliminarytransmission bit rate not exceeding the third video bit rate.
 20. Thenon-transitory computer-readable medium of claim 1, wherein theinstructions, when executed, further cause the communication entity to:determine an average transmission bit rate averaging a plurality oftransmission bit rates for different video data streams within a timeslot, and determine the preliminary transmission bit rate as the averagetransmission bit rate.